//=============================================================================
// VectorIter.cpp
// Written by:    Unknown, 
//
// Last Modified: Fall 2020
//
// Description: This sample demonstrates how to use STL's vector container 
//              to store a sequence of integer values. 
//
//              You may also find the use of std::vector::iterator
//
//              Also note the use of typedef vector< int > myVectorType;
//              This tends to save typing and may allow
//              type changes to be isolated to one line of code change.
//
//
// Tasks: find the TODOs and do them
//
//
//=============================================================================
#include <iostream>
#include <vector>

using namespace std;

// ------------------------------------------------------------------------
// TODO:
// First create a new type, which represents a vector container of ints
// This reduces code clutter and helps in maintaining code
// ------------------------------------------------------------------------
typedef vector< int > myVectorType;



// ------------------------------------------------------------------------
// ProtoTypes of global functions
// ------------------------------------------------------------------------
// TODO: create a prototype declaration of printContents as defined (far) below
void printContents( myVectorType v );
void ContinueAsFibonacci(myVectorType *vFibPtr, int N);


// ------------------------------------------------------------------------
// main function - it all begins here
// ------------------------------------------------------------------------
int main( void )
{
    //---------------------------------------------------------------------
    // TODO: Create the initial vector 
    myVectorType myFib;

    // TODO: Initialize the first 2 numbers in our vector to be 0 and 1
    //       Use the vector function push_back
    myFib.push_back( 0 );
    myFib.push_back( 1 );
    
    // TODO:
    // Call the ContinueAsFibonacci function to push the next 4
    // numbers of the sequence onto myFib...
    // Notice we must pass a pointer to myFib... so set that up too
    myVectorType* myFibPtr = &myFib;
    ContinueAsFibonacci(myFibPtr, 4);

    // Print out the contents for inspection
    printContents( myFib );

    // TODO:
    // Repeat the above so you get the next 5 numbers in the sequence
    ContinueAsFibonacci(myFibPtr, 5);
    printContents( myFib );

    return 0;   // zero indicates program success to the operating system

} // end main()

//-------------------------------------------------------------------------
// printContents
//-------------------------------------------------------------------------
void printContents( myVectorType v )
{
    //---------------------------------------------------------------------
    // Using iterators, 
    // which point to the beginning and ending of the vector,  
    // loop through the vector and print out its contents

    // TODO: use the vector functions begin and end to initialize the below correctly
    myVectorType::iterator it_cur   = v.begin();
    myVectorType::iterator it_end   = v.end();

    cout << "Contents of the vector: \n     ";

    // TODO: loop until it_cur equals it_end
    while (it_cur != it_end)
    {
        cout << *it_cur << " " ;
        
        // TODO: increment the it_cur iterator
        ++it_cur;
    }
    cout << endl;
}

//-------------------------------------------------------------------------
// ContinueAsFibonacci
//
// Assume the last 2 values of vFibPtr properly start the Fibonacci sequence
// at the place the user wants to begin
// So we really only care about the last 2 elements in the vector
//
// Using iterators such as those returned by begin and end, 
// and the vector function push_back
// push the next N numbers in
// the Fibonacci sequence into vector vFib
//
// TODO: implement this function
//
//-------------------------------------------------------------------------
void ContinueAsFibonacci(myVectorType *vFibPtr, int N)
{
   // TODO:
   // Do some simple error checks
   if (vFibPtr == NULL)     {  return;  }  // if vFibPtr i null return
   if (N <= 0)              {  return;  }  // if n is less than or equal 0 return
   if (vFibPtr->size() < 2) {  return;  }  // if vFibPtr's size is < 2 return
   
   // TODO: loop from 0 to N-1
   for (int i=0; i < N; i++)
   {
	   int value = 0;
       myVectorType::iterator it_end = vFibPtr->end(); // this is 1 past last value
       
       // TODO: properly adjust it_end, and use it to calculate
       //       the next Fibonacci number... store that in the variable named value
       it_end--;
       value = (*it_end);
       it_end--;
       value += (*it_end);
       
       // TODO: Using vector function push_back
       //       push value onto the vector pointed to by vFibPtr
	   vFibPtr->push_back(value);
   }   
}

//-------------------------------------------------------------------------
//-------------------------------------------------------------------------
// end file